So as I understand it barbarians can't cast spells while raging, but, aberrant mind sorcerer has the psionic sorcery ability, so since that is psionics, which are NOT magic, would you still be able to use the psionic casting while raging, I realise that technically it is still "casting" spells, but nonetheless, it isn't magic so is it compatible, not compatible, or something that should be left to the dm to decide?
You've answered your own question, psionic casting is still casting and you can't cast while raging, so it won't work RAW. Your DM is free to rule otherwise of course, but it would be a house rule and not RAW. The non-spell casting sub-class features would work fine.
By the way, the flavour text of Aberrant Mind says the following:
An alien influence has wrapped its tendrils around your mind, giving you psionic power. You can now touch other minds with that power and alter the world around you by using it to control the magical energy of the multiverse.
There's nothing in the description that suggests that the psionic power is anything more than a different way to do magic.
Ah thanks, I'd forgotten about that bit of the text, so it is still magic just harnessed through psionics. So soulknife and psi warrior could be used with raging but aberrant mind can't, thats annoying honestly, I really wish the mystic had been added. (nerfed a bit obviously).
You cam of course still use magics at a distance, ehile (preparing to) move into meelee range.
I recently did this as a personal experiment with a Druid 2 / Barb 2 multiclass, which was good, because i had to use either 2 turns to move into meelee range, or dash, without being able to attack.
I noticed that controling the battlefield with spells to limit other players movement are excellent for this.
Shellilagh is my go to bonus action cantrip before i enter meelee range with my Quarterstaff, and on the turn i enter meelee range, i bonus action Rage
For that I recommend warlock, 1-3 levels in any warlock as a barbarian is always good, you get eldritch blast which at level 2 you can buff with agonizing blast and eldritch spear for long range sniping, you also get armour of agathys which is great with rage because it lasts longer and at level 3 if you go that far you get the pact boon which can be pact of the blade and improved pact weapon invocation if you give up eldritch spear. Wear medium armour get 14 dex and maybe 14 or 16 cha if you roll big numbers and it should work. But the far more powerful option is to go full warlock, play as hexblade and get 1-3 levels in barbarian, ignore strength beyond the 13 you need to multiclass, pump charisma and constitution and in combat use an upcasted armour of agathys to become the 2nd best damage redirection machine in the game after a level 10 moon druid with armour of agathys and wildshaped into a fire elemental. This does lose you the rage damage bonus but the ability to spam long range eldritch blast while also being a lethal front line brawler and having some other powerful magic spells and options available makes it one of my favourite multiclasses, finally making barbarian your base class gets you proficiency in con saves which is great for holding concentration.
So as I understand it barbarians can't cast spells while raging, but, aberrant mind sorcerer has the psionic sorcery ability, so since that is psionics, which are NOT magic, would you still be able to use the psionic casting while raging, I realise that technically it is still "casting" spells, but nonetheless, it isn't magic so is it compatible, not compatible, or something that should be left to the dm to decide?
Mitth'raw'nuruodo
You've answered your own question, psionic casting is still casting and you can't cast while raging, so it won't work RAW. Your DM is free to rule otherwise of course, but it would be a house rule and not RAW. The non-spell casting sub-class features would work fine.
By the way, the flavour text of Aberrant Mind says the following:
An alien influence has wrapped its tendrils around your mind, giving you psionic power. You can now touch other minds with that power and alter the world around you by using it to control the magical energy of the multiverse.
There's nothing in the description that suggests that the psionic power is anything more than a different way to do magic.
Ah thanks, I'd forgotten about that bit of the text, so it is still magic just harnessed through psionics. So soulknife and psi warrior could be used with raging but aberrant mind can't, thats annoying honestly, I really wish the mystic had been added. (nerfed a bit obviously).
Mitth'raw'nuruodo
It really is a case of concentration. While raging you really cant maintain concentration on anything other than the anger and desire to smash.
You cam of course still use magics at a distance, ehile (preparing to) move into meelee range.
I recently did this as a personal experiment with a Druid 2 / Barb 2 multiclass, which was good, because i had to use either 2 turns to move into meelee range, or dash, without being able to attack.
I noticed that controling the battlefield with spells to limit other players movement are excellent for this.
Shellilagh is my go to bonus action cantrip before i enter meelee range with my Quarterstaff, and on the turn i enter meelee range, i bonus action Rage
For that I recommend warlock, 1-3 levels in any warlock as a barbarian is always good, you get eldritch blast which at level 2 you can buff with agonizing blast and eldritch spear for long range sniping, you also get armour of agathys which is great with rage because it lasts longer and at level 3 if you go that far you get the pact boon which can be pact of the blade and improved pact weapon invocation if you give up eldritch spear. Wear medium armour get 14 dex and maybe 14 or 16 cha if you roll big numbers and it should work. But the far more powerful option is to go full warlock, play as hexblade and get 1-3 levels in barbarian, ignore strength beyond the 13 you need to multiclass, pump charisma and constitution and in combat use an upcasted armour of agathys to become the 2nd best damage redirection machine in the game after a level 10 moon druid with armour of agathys and wildshaped into a fire elemental. This does lose you the rage damage bonus but the ability to spam long range eldritch blast while also being a lethal front line brawler and having some other powerful magic spells and options available makes it one of my favourite multiclasses, finally making barbarian your base class gets you proficiency in con saves which is great for holding concentration.
Mitth'raw'nuruodo